Freedom of speech on university campuses has been high on the agenda this week. Tonight the Universities Minister Bill Rammell has said he wants academics to do more to challenge extremist ideologies in open debate. But how serious is the threat from campus extremism? A former senior member of the radical Hizb ut Tahir group has told this programme that radicalisers have effectively abandoned the campuses to concentrate on younger recruits - and senior security sources claim there are new recruitment methods now at work.